Washington was an outrage factory long before President Donald Trump arrived, and it’s become exponentially more so now that he’s here. But constantly being on an outrage footing can undermine your cause.

That’s what happened Monday with critics of a speech Attorney General Jeff Sessions gave in which he cited the “Anglo-American” origins of America’s sheriffs. “The office of sheriff is a critical part of the Anglo-American heritage of law enforcement,” Sessions said.

Several things conspired to make this seem like a Very Big Deal: Sessions has a history of racial controversy, the adjective didn’t appear in Sessions’ prepared remarks, and there is a clear and demonstrated history of Trump and his administration exploiting dog-whistle politics.

Perhaps the two most full-throated responses came from Sen. Brian Schatz, D-Hawaii, and the NAACP. Schatz called it “appalling.” The NAACP said they were Sessions’ “latest racially-tinged comments” and that it “qualifies as the latest example of dog whistle politics.” (Continued below.)

The media quickly keyed on the apparent controversy. “Sessions draws fire for ‘Anglo-American heritage’ remark at sheriffs’ conference,” read ABC News’s headline. “Attorney General Sessions faces accusations of racism after honoring ‘Anglo-American heritage’ of policing,” the New York Daily News said. Splinter’s Emma Roller went quite a bit further, writing that Sessions “Let His Racism Peek Through a Little More Than He May Have Intended To.”

But to the legal community, Sessions’ comments are far from controversial. The office of the sheriff, after all, was first established in Anglo-Saxon England and thrived in the United States even after it declined in England. University of Denver law professor David Kopel detailed it all in The Post in 2014.

And if talking about the Anglo-American origins of American law enforcement is racist or a dog whistle, then someone should tell former president Barack Obama. The National Review’s Charles C.W. Cooke unearthed multiple examples of Obama himself using the same word as Sessions:

In 2006 on the Senate floor: “I sincerely hope we can protect what has been called the ‘great writ’ - a writ that has been in place in the Anglo-American legal system for over 700 years.”

In 2008, he called habeas corpus “the foundation of Anglo-American law.”

In 2009, before being inaugurated, he talked about a way to deal with Guantanamo Bay “that adheres to rule of law, habeas corpus, basic principles of Anglo-American legal system, but doing it in a way that doesn’t result in releasing people who are intent on blowing us up.”

A top Obama administration Justice Department official, Bill Baer, also cited the “Anglo-American common law system” in a 2014 speech about legal relations between the United States and China.

Is it possible Sessions inserted the term to provoke? In the sense that anything is possible, yes. But the term is so noncontroversial in legal circles that Obama and his administration used it with some regularity. And it probably won’t surprise you to know that Schatz is not among the sizable minority of members of Congress who are lawyers.

This is the danger in overreacting for Trump’s opponents. There have been more than enough actual dog-whistles during Trump’s presidency, and Trump’s most strident opponents would very much like for the media to call a spade and spade. When Trump refers to “shithole countries,” they want it to be described as a racist comment. They are convinced that Trump has forfeited the benefit of the doubt.

It’s 100 percent true that Trump and his administration’s track record should impact how comments like that are covered. The president exploits the gray areas of American politics and plausible deniability way too much for it all to be innocent and coincidental. And that demonstrated history should color every momentary controversy, like over his comment about “shithole countries.”

But erasing any benefit of the doubt and having your outrage on a hair-trigger can play into Trump’s hands. The more reactions like this occur, the more credible Trump’s case becomes that opponents are reading the worst into everything he and his administration say and do, and the more his claim to be a victim of political correctness and an overzealous media rings true to his already-dug-in base.

And people who truly want to hold Trump and his administration accountable on important issues should be concerned about that.